Transcript part_5b_LONworks - University of Florida

LonWorks PLC
(c) 2013 R. Newman
University of Florida
What is LonWorks Protocol
• Multiple medium protocol for home automation
(domotics) and control
• Local Operating Network (LON)
• Narrowband PLC, TP, CX, fiber optics, RF
– TP 78 kbps using Differential Manchester
– PLC 5.4 or 3.6 kbps depending on frequency band
• Developed by Echelon Corp.
– 60 million devices by 2006
• Multiple standards
– International and open industry standard
– European standards
– China national standards
LonWorks Standards
• International and open industry standard
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Submitted to ANSI 1999 - ANSI/CEA-709.1
Basis for IEEE 1473-L (in-train controls)
SEMI (semiconductor equipment manufacturing)
One of several data link/physical layers of the BACnet ASHRAE/ANSI
standard for building automation.
– ISO and IEC standards ISO/IEC 14908-1, -2, -3, and -4
(communications protocol, twisted pair signaling technology, power line
signaling technology, and Internet Protocol (IP) compatibility)
• European standards
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AAR electro-pneumatic braking systems for freight trains
IFSF (European petrol station control)
EN 14908 (European building automation standard)
Part of Household Appliances Control and Monitoring – Application
Interworking Specification (AIS) standards of CECED (European
Committee of Domestic Equipment Manufacturers)
• China national standards
– Controls standard, GB/Z 20177.1-2006
– Building and intelligent community standard, GB/T 20299.4-2006
LonWorks Major Elements
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LonTalk protocol
Neuron chips
LonWorks transceivers
Network management/applications
SNVTs (Standard Network Variable Types)
LonTalk Protocol
• Media
– Twisted pair, powerline, radio frequency, fiber optics,
coaxial cable
– Highest data rate 1.2 Mbps
• Reliability
– Supports end-to-end acks with ARQ
– Broadcast acks also
ACK implosion problem!
• Medium access
– Proprietary collision prediction algorithm
– Collision detection on some media (e.g., TP)
– Optional priority feature
• Network management/applications
• SNVTs
LonTalk Addressing
• Hierarchical
– Domain, subnet, node; also Group
– All nodes in domain, subnet addressable
• Channel = physical medium
• Domain = logical set of nodes on one or more
channels
• Communication only possible in domain
• Multiple domains may share channel(s)
• Subnet – must share a channel
– cannot span a router, 127 node max
– Domain may have up to 255 subnets
• Group – may use multiple channels
– Node may be in up to 15 groups, <64 nodes/group
– Domain may have up to 255 groups
LonTalk Delivery Services
• Unacknowledged
– Most commonly used
– Widest bandwidth
• Unacknowledged/Repeated
– No acks, but multiple copies sent per settings
• Acknowledged
– Used when reliability required
– Timeout set at installation time
• Priority
– Time slots may be set aside for priority traffic
– Used sparingly – reduces bandwidth available
LonTalk Network Management
• All nodes are network management capable
• Find unconfigured nodes and download network
addresses.
• Stop, start and reset node applications
• Configure routers and bridges
• Download new application programs
• Change the network variable configuration table:
– type of protocol service used to send the network
variable
– whether the variable is sent in a priority slot.
LonWorks Transceivers
• Twisted Pair
– 78 Kbps/4600 ft (1400 m)
– 1.25 Mbps/430 ft (130 m)
Longer distance => more attenuation
=> lower SNR (noise is constant)
=> lower data rate (Shannon's Thm)
• Powerline
– Spread spectrum (proprietary) or narrowband
– 10 Kbps, Up to 2000 m on clear line
• Radio Frequency
– 400-470 MHz licensed
– 900 MHz unlicensed
• Configuration
– Installation announces device’s presence
– Binding network variable tells device what data to
share with whom
LonWorks Datalink Layer
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Error Detection (CRC)
Flexible allocation of bandwidth
Priority access mechanisms
Graceful behavior under overload
– p-persistent CSMA
CSMA: When current transmission done
p-persistence: Tx with prob. p
Optimal p is 1/N for N contenders
• Message collision avoidance
• Optional collision resolution, collision
detection
CD not possible on RF or PLC medium
=> Collision avoidance important
LonWorks Network Layer
• Node address information
• Message routing to segment
– determining which nodes on the network
receive various messages
• Network bandwidth usage control
• Routers
– segment traffic
– communicate between different channels
LonWorks Transport Layer
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Broadcast addressing
Unicast addressing
Multicast addressing - groups
Repeated service
Acknowledged service
Unacknowledged service
Duplicate packet detection
Authentication
LonWorks Session Layer
• Acknowledgment of received message
• Application-to-application communication
• Retry if the correct response is not
received from the remote node
• Request to a destination group and
receive individual responses from the
group
• Request - response message
authentication
LonWorks Presentation Layer
• Input, output, and configuration variables
for the node
• Standard data representations for physical
quantities
• Network variable description
LonWorks Application Layer
• Memory storage for application program
• Built-in real-time operating system
• Device drivers for the I/O hardware on the
Neuron Chip
• Standard Network Variable Types (SNVTs)
SNVTs
• Standard Network Variable Types
• A key to interoperability
• Standardizes variables used to name and
describe things and their states
• Maintained by LonMark International
• Each standard known as an SNVT
– Pronounced “snivit”
– E.g., temperature is a 16-bit quantity
representing -274 to 6279.5 Celcius
SNVT Examples
Variable Type Units
Variable Type Units
Switch State
Boolean
Temperature Degrees Celsius
Device State
Boolean
Real Time
MM,DD,YYYY
Energy
Kilowatt-Hours
Event Count Counts
Power
Watts
% of Full Scale Percent
VoltageDC or AC RMS
VolumeGallons, CCF, liters
Current
Amps AC, RMS
Flow
Gal or liters/hour
Resistance
Ohms
Weight
Kilograms, Lbs.
Sound Level dBrnc
Speed
Miles or Km/hour
VoltagedB microvolts
Alphanumeric ASCII Characters
Alphanumeric Kanji Characters
Alphanumeric International characters
Day of Week
Elapsed Time
Phone State
Enumerated List (Mon-Sun)
Second, Milliseconds, Days or Hours
Enumerated List (On-hook, off-hook, busy, ringing, etc.)
PressureLbs./sq.in, Pascals, Inches-Hg
Relative Humidity
Percent
LonWorks Links
• http://www.ieclon.com/LonWorks/LonWorksTuto
rial.html